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Performance Optimization cheat sheet & developer notes

Performance Optimization cheat sheet and 2 curated developer notes — core concepts, patterns, and interview prep. Maintained by the DevRecall team.

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01 · Performance Optimization

Core Web Vitals & Loading Performance

Core Web Vitals & Loading Performance. LCP, INP, CLS — what Google ranks on, what each one measures, and the concrete levers to move them.. The Three Vitals. Metric Measures Good Needs Poor ────── ───────────────────────…

02 · Performance Optimization

Bundle Size, Rendering & React Performance

Bundle Size, Rendering & React Performance. Code-splitting, lazy loading, render minimisation, and the React-specific patterns that come up in audits.. Code-Splitting & Lazy Loading. // Dynamic import — splits into a sep…

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Interview Questions

TypeScript Interview Questions. Comprehensive TypeScript interview questions covering type system, generics, utility types, and best practices:. Fundamentals. 1. What is TypeScript?. TypeScript is a…

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Advanced Types (Generics & Utility Types)

TypeScript Advanced Types. Generics. // Generic function function identity<T>(arg: T): T { return arg; } const num = identity<number>(42); // Explicit const str = identity('hello'); // Inferred //…

Concepts to know for Performance Optimization

Memoization in React: memo, useMemo, useCallbackWhy React re-renders a whole subtree, why a new object or function each render defeats React.memo, when memoizing pays off, and what the React Compiler changes.Intermediate·13 min The Critical Rendering PathHow a browser turns HTML, CSS and JS into pixels, which resources block which step, and why some CSS changes cost a layout while others cost nothing.Intermediate·14 min Core Web VitalsWhat LCP, INP and CLS actually measure in the browser, the fixes that move each one, and why a green Lighthouse score can go with red field data.Intermediate·14 min Image Optimization: Formats, srcset and PriorityPick the format, let srcset and sizes choose the pixels for each screen, and load the hero first without layout shift: the three decisions behind fast images.Intermediate·13 min Tree Shaking, Code Splitting and Bundle SizeWhy JavaScript bytes cost more than image bytes, how bundlers drop unused exports, what quietly stops them, and how splitting and budgets keep bundles small.Intermediate·13 min Web Workers: Getting Work Off the Main ThreadWhy one long JavaScript task freezes input, when yielding is enough, and how workers, transferables and SharedArrayBuffer move heavy work off the main thread.Intermediate·13 min

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